U.S Defense Secretary Ashton Carter delivers a speech during a conference in Paris, Thursday, Jan 21, 2016. Carter said Wednesday that defense ministers from France and five other nations have agreed to intensify the campaign against Islamic State group in Iraq and Syria, and that the coalition will work together to fill the military requirements as the fight unfolds over the coming months. (AP Photo/Christophe Ena)

PARIS (NBC NEWS) — The offensive to oust ISIS from its capital will get underway within weeks, Defense Secretary Ash Carter told NBC News in an exclusive interview Wednesday.

“It starts in the next few weeks,” he said, referring to the timeline for the assault on the militants’ Syrian stronghold of Raqqa. “That has long been our plan and we will be capable of resourcing both.”

Carter added: “It’s been long a part of our plan that the Mosul operation would kick off when it did. This was a plan that goes back many months now and that Raqqa would follow soon behind.”

Raqqa is the de facto capital of the extremists’ so-called caliphate which stretches from Syria into Iraq.

Carter just returned from Iraq, where some 5,000 U.S. personnel are supporting the massive military campaign to retake Mosul from ISIS that began on Oct. 16.

When asked whether U.S. special forces or other troops would be sent inside Mosul or Raqqa to gather intelligence or hunt “high-value combatants,” Carter replied: “They are not near [Mosul] at this time … Our forces do accompany …. the Iraqi security forces and the Peshmerga. So they will get nearer to the city as those forces get nearer to the city … We are not going to be part of the occupation or hold forces.”

Carter spoke to NBC News on Wednesday in Paris, where he has been meeting with his counterparts from other Western countries.

Some European leaders have said they were concerned the effort to take Raqqa had not begun yet, which would allow the extremists to continue planning and inspiring the sorts of attacks that have hit France and Belgium during the last year.

Carter also told NBC News that he was “outraged” by revelations the Pentagon was forcing thousands of soldiers to return bonuses given out more than a decade ago to get them to reenlist for six years and fight in Iraq and Afghanistan.

“We need do justice. And we need to do it fast,” said Carter, who was heading to a meeting with NATO defense chiefs in Brussels later on Wednesday.

“We need do justice. And we need to do it fast,” said Carter, who was heading to a meeting with NATO defense chiefs in Brussels later on Wednesday.